Can you paint multiple texture layers simultaneously?
I believe you are looking for a mix of Sculpt Mode and Texture Paint mode. They work similarly as ZBrush, allowing you to sculpt in high poly mode, export a normal map, and also paint the UV maps directly over the model. There is no need for extra plugins, Blender does that natively. Just click on "Object Mode" and try the other modes.

You might also try Sculptris, by Pixologic. It's freeware (gratis, but not libre), like a very bare-bones version of ZBrush.